Research On Reliability Evaluation Of Suspension Bridge Slings Based On Electrochemical Corrosion Experiment

The sling corrosion disease of the suspension bridge is very prominent,and the serious ones will endanger the safety of the operation of the bridge.Therefore,the reliability assessment of the corroded cable body is very critical.Based on investigating the types,causes,and corrosion rates of slings,this paper uses electrochemical corrosion experiments and finite element simulations to study the corrosion development law of the broken section of the cable body,and the degree of performance degradation of the corroded steel wire and the cable body.Relying on the engineering situation and the reliability calculation method,a quantitative assessment of the corrosion level of the cable body was carried out.Mainly include the following content and results:(1)Investigate the current status of research on reliability evaluation of corroded cables,analyze the types of damage,effects and failure cases of cable structures,point out the necessity of cable reliability evaluation,and preliminarily clarify the decisive factors affecting cable reliability;The theory of structural reliability and the calculation method of reliability indicators lay the foundation for the evaluation of corrosive cable bodies.(2)Based on the actual engineering steel wire corrosion rate and Faraday's law,the actual and experimental corrosion currents are analyzed,and five groups of electrochemical corrosion experiments of different corrosion time segments are designed and implemented;the longitudinal and lateral development of corrosion in the cable body are summarized and analyzed.The time-varying model and distribution of the diameter loss of the cable body wire were established,and the relationship model between the corrosion depth of the experimental cable body and the actual corrosion time was established.Based on the diameter loss rate and the strength loss rate,the grade and degree of the corrosion wire of the cable body were divided,and Based on this,the grade distribution of broken wires in the cable body is analyzed.(3)Investigate the current technical standards for cable bodies,give different types of cable body cross-sectional corrosion layers and calculation formulas for the number of steel wires,and combine the experimental steel wire grade distribution to give the effective cross-sectional area calculation formula of the cable body and verify it;Timevarying model of nominal elastic modulus under actual corrosion time of cable body;Monte-Carlo method is used to analyze the calculation formula of tensile strength and bearing capacity of cable body steel wire considering Daniel effect;Corrosion cable body grade is given according to the corrosion status of cable body The quantified index and the establishment of the finite element model of the cable body are analyzed to analyze the stress and strain characteristics of the cable body and the change law of the stress recovery distance under some indexes,and the performance of the corroded cable body is further analyzed.(4)Investigate and analyze the factors affecting the reliability of suspension bridge slings and their distribution,establish a finite model of a Yangtze River bridge and analyze its force characteristics,and obtain the most unfavorable cable position.According to the failure function function of the component and the corroded cable body Parameter calculations have obtained the reliability index and safety factor of the cable body with different corrosion levels,combined with the quantified index of the cable body grade,put forward a quantitative standard for the reliability evaluation of the cable body corrosion grade,and carried out the performance impact assessment of the supporting project.